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[Grax]

I see.

I was just reviewing the mod files. The melting point for Alunite appears to be wrong. The melting point given is that for Aluminium oxode. However, alunite is apparently (wait for it) hydrated aluminium potassium sulfate, KAl3(SO4)2(OH)6. I think the melting point for Alunite could be lower. A lot lower. Possibly less than 100. I don't have anything concrete though, and I'm not a chemist.

Alunite can be also K2SO4*Al2(SO4)3*4Al(OH)3, so it must be [METAL_ORE:ALUMINUM:35]

Other info here: http://www.webmineral.com/data/Alunite.shtml

Nobody melts aluminum ores, its refining process use electric power.

[0x517A5D]

Nobody melts aluminum ores, its refining process use electric power.

Actually the process I'm acquainted with does melt the ore.  As a solid it's nonconductive, as a liquid you can do electrochemistry on it.  So they melt it in a special cauldron, shove a big old carbon electrode in it, and zap it.  Probably not much voltage, but huge amperage.  The molten aluminum is separated out somehow, probably by density.

If I run across this stuff again, I'll gather up the stated melting points and normal operating temperature for the process.

[Great Cthulhu]

Wow. Lots of activity in here.

I'll take a look at the new data when I'm home and update the mod.

On a related note: a couple of days ago, I've passed the data we already had to Toady, who found it useful, so hopefully the next version of DF won't need the mod.

[Grax]

Nobody melts aluminum ores, its refining process use electric power.

Actually the process I'm acquainted with does melt the ore.  As a solid it's nonconductive, as a liquid you can do electrochemistry on it.  So they melt it in a special cauldron, shove a big old carbon electrode in it, and zap it.  Probably not much voltage, but huge amperage.  The molten aluminum is separated out somehow, probably by density.

If I run across this stuff again, I'll gather up the stated melting points and normal operating temperature for the process.

There're no ore melting stage in the aluminum extraction process, if we mean "melting" as the heating ore till the metal sluice out of it.

And carbon anode is the bottom of the cauldron. ;-)

[Great Cthulhu]

I can't find my original source for the microcline data, but I found a better one here. It states that microcline begins melting at 1,000°C and becomes completely liquid at 1,300°C.

Unfortunately, I can't seem to find the source for the obsidian data anymore. The best I can find is this, which seems to indicate that obsidian softens somewhere below 1145°C.

Thanks! I found another one for obsidian. It states that the melting point is between 940-1080 C. (http://www.swxrflab.net/blmpaper.pdf)

The link you provided doesn't show me any of the text of the book. Seems like Google Books has changed their interface a lot from the last time I used it too. I'll still include it with the book named as the source.

[Great Cthulhu]

i do not know if these are in yet, but

assuming gabbro = basalt then: Gabbro and Basalt melts at about 984° to 1260°

http://www.minsocam.org/MSA/collectors_corner/arc/tempmagmas.htm

also from there: granite at about 1215° to 1260°

also a link from the new thread in sugestions on this exact topic: http://www.bay12games.com/forum/index.php?topic=41971.0

Thanks!

I already got those two, but it's interesting that your source contradict my own on granite, which states that it melts at about 800 C. They do agree on the melting point of gabbro/basalt.

I think I'll go with my source on granite. My reason for that is that, according to my source and wikipedia, granite and rhyolite are chemically pretty much identical, and both our sources agree that the melting point of rhyolite is not much higher than 800 C. It follows that the same will likely hold of granite, which matches with my source but not yours.

[Great Cthulhu]

Hopping over from the suggestions thread I made. I think the discussion is best carried out here.

It seems the work here is pretty comprehensive. There's not a lot more to add. However, the mod is missing data on Gems. (Not sure how much use this will be to anyone though). But it's the least I can do after the work you guys have put in.

I check the list of wikipedia pages for melting point data. There's not a lot there, night nothing in fact, but here's the list of what was there if anyone's interested.

Citrine/Quartz/Rock Crystal/Amethyst   1650 (±75) °C
Ruby    2044 °C
Sapphire 2030–2050 °C

And finally, not from wikipedia, but danm, if Diamonds have been melting up to this point, it's now a major embarrassment.

Via minerals.net

Diamond has many unequaled qualities. It is the hardest known substance, it is the greatest conductor of heat, it has the highest melting point of any substance (7362° F - 4090° C)

Oh my goodness!!

Thanks!

Right now diamonds apparently burn. They have no melting point, but they do have ignition and boiling points in the RAWs, at 800 C and 3727 C, respectively.

I'll add the other data to a future version of Molten Rocks. I the meantime, feel free to add any data you find a source for to this spreadsheet.

[Shurhaian]

Regarding sphalerite - how does DF handle things with only one listed state point? If a substance with no melting point just boils away at the boiling point as normal, that's probably the closest we can hope for. If, on the other hand, its behaviour is undefined or it needs to be liquid to boil away(and since it never melts, doesn't), setting its melting and boiling points one degree Urist apart may make sense.

[Great Cthulhu]

I'm not sure about this, but I think DF uses a fixed default value for missing entries. It is possible to set MELTING_POINT:NONE (or something to that effect) though. Diamonds are an example of a substance that (in DF) can't melt, but does have a boiling point.

[2xMachina]

Wait, diamonds can boil but not melt?

How does that work? Only dry ice and stuff like that (or really low pressure) causes that.

[Shurhaian]

Sphalerite was mentioned as sublimating at a given temperature.

Plenty of scented compounds do the same thing. They're solid blocks which gradually turn to gas at or around room temperature. Some of them use heaters to do the same or speed up the process. (A possibility is that the sublimation point is below room temperature, but there's substantial heat of vaporisation to overcome, so the process takes time without pumping energy into it.) Camphor, while solid, emits fumes that, among other uses(including for its scent), helps keep tools from rusting.

It might not be the best-known pattern, but dry ice is hardly unique in doing it, even at standard pressure. Even substances that do have a liquid state can go through sublimation and deposition(frost crystals on a window are water vapour going directly to a solid state); there are other substances that simply don't have a liquid state unless put under pressure.

[LegoLord]

Yes, the process of sublimation is not restricted to dry ice.  I believe elemental iodine is one such thing (though it may be some other halogen, I can't quite remember).

Charts that show melting and boiling points are actually fairly complex, since those are based on both temperature and pressure.  The line generally looks like a 'y', with the three sections that the line splits the chart into representing the ranges of temperature and pressure that a substance will be a certain state in.  I think it might be theoretically possible for a good many things to sublimate, actually.

Hm.  You know, it would be neat if DF could track air pressure without putting much of a dent in FPS.

[Shurhaian]

Elemental iodine does indeed sublimate readily, although it CAN, with care, be melted as well. (The lighter halogens are gaseous and highly reactive at room temperature, I don't know about the heavier ones.)

Melting points are actually fairly consistent - they can be assigned a value without being TOO far from reality. They're also referred to as "triple points" - the points at which a substance can be in gaseous, liquid, OR solid state.

Many things do sublimate to some degree, as I mentioned; even things below their melting point can do so slowly(thus "freeze drying"; the freezing process leaches water out of the thing being dried, and the ice is then free to sublimate, though physically removing the excess might help it along - see also frost deposition).

Neat as tracking pressure would be, though, I don't think there IS a good way to do it without ramping up CPU use. Not in any way that'd seriously add to the game, anyway... Similarly, that slow sublimation isn't terribly helpful. For game purposes, it's probably best to stick to simple state changes, but explicitly include the possibility that something doesn't have a liquid state at atmospheric pressure.

[LegoLord]

Actually, since that last post of mine, I noticed a discussion about air pressure under suggestions.  Since air pressure normalizes at the speed of sound, someone noted, air pressure might not need to be tracked on a per-tile basis.

side note:  The triple point is a single point where the "sublimation" line (between the solid and gas sections of the chart) meets the "freezing" and "boiling" lines (on either side of the liquid section of the chart).  There's one per substance.  The melting points of a material is along the "freezing" line.

[2xMachina]

But surely diamonds don't sublimate at room temperature...

As for air pressure, it should only change over z-levels, unless you've got air tight places, which does not exist at the moment.